The present invention relates to a golf club head, more particularly to a structure of the face portion capable of improving the durability.
In Japanese patent application publication No. 2002-165906, there is disclosed a wood-type hollow metal golf club head whose face portion is formed from a metal plate rolled in two or more different directions. This prior art teaches that if the rolled direction is one direction, the rolled plate is decreased in the resistance to bending deformation in a specific direction, and that when the rolled direction is aligned with the heel-and-toe direction of the head, the face portion is decreased in the durability. But, in the case of a metal plate rolled in two or more directions and thus having less anisotropy, the durability of the face portion can be improved and yet it becomes not necessary to concern the orientation of the metal plate. Further, it is suggested that the metal plate is preferably formed from a beta titanium alloy by cold rolling.
The inventor made a study and found that the durability of the face portion can be improved by specifically orienting a unidirectionally rolled titanium alloy having alpha phase in spite of the one rolled direction, and accordingly the manufacturing cost and efficiency can be improved.